Owners of wearable Internet-connected devices already face choices about where or when it is appropriate to wear them—while legal experts say there aren't many protections for people whose activities the technology records.

Noble Ackerson, a 33-year-old software developer in Washington, D.C., who has been wearing Google Glass for the past month, says he has developed his own "common sense" etiquette standards for Google Inc.'s new digital headset.

For instance, he takes Glass off in a public restroom, in a movie theater and in casinos, where having such a device could give him an unfair advantage. "Google Glass has technology that isn't new, and the etiquette we've applied to existing technologies should roll into it," he says.

Products like Glass are sparking a discussion about what is possible with technologies such as facial recognition, and whether governments need to intercede. While several members of Congress pressed Google on Thursday for answers about how its technology works, some business owners like bars or casinos are already banning it.

Right now, Google Glass, which places a small computer screen above one eye and has a built in motion sensor, camera and microphones, acts like an extension of a person's smartphone.

It lets the user take photos and record videos by touching the side of the device or speaking commands aloud, as well as allowing them to give Web users access to the device's camera so they can "see" what the wearer is looking at. People also can use Glass to make phone calls, access Google's Web search, get turn-by-turn navigation information and receive text messages on the screen, as well as send texts using their voice.

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The device isn't widely available, but Google plans to publicly launch it next year.

Early testers of the device say the potential benefits—such as giving paraplegics the ability to take photos using their voice or making it easier to document police brutality, among other uses—outweigh such privacy and security risks.

But one potential use has captured the imaginations—and fears—of many: facial recognition.

While such technology still faces numerous hurdles, the capability to use it for purposes once relegated to science fiction have already been proven in a real-world context, most recently by Carnegie Mellon University researchers in 2011.

By combining public information from social networks and facial-recognition technology, the researchers used a webcam on a college campus to identify people by name, and then—by using information from their social-network profiles—also predict sensitive personal data, such as hobbies and Social Security numbers.

"The genie is out of the bottle," says Carnegie Mellon professor
Alessandro Acquisti,
who was part of the research team. "My bet is facial recognition and augmented reality will become commonplace and popular."

While real-time facial recognition technology isn't yet scalable, remaining hurdles already are being overcome, he says, and societies will need to "discuss and try to create frameworks so that good applications will survive and creepy ones will not."

Google Glass product management director
Steve Lee
said in a statement Friday that "we won't add new face-recognition features to our services unless we have strong privacy protections in place."

On Thursday, Mr. Lee and other Google employees say that while any device, including today's smartphones, can be misused to hurt or spy on other people, the company would endeavor to bar such applications from being available on its public app store for the device.

Mr. Lee says the device would also be a "lousy" way to spy on people because the wearer must face whatever it is they are recording. The device's small screen lights up when it is taking a photo or recording a video using the camera, allowing people near the wearer to know that it is on.

Mr. Lee added that he expected there would be facial-recognition applications available on Glass in the future, possibly created by third party software developers.

Google has said data recorded by the device would be bound by its current privacy policy, meaning it could be collected in an anonymous way and the company would hold data about specific individuals only if they explicitly agree to it, the same as with smartphone-related data.

Most of the wearable devices on the market, with names like LUMOback and Fitbit, are meant to capture health-related information about the person wearing them, such as heart rate and posture. Now new devices led by Google Glass capture data around the wearer—including the people they interact with.

For instance, a forthcoming $279 device called Memoto, designed to be worn on a chain around the neck or clipped to clothing, automatically snaps photos every 30 seconds, or nearly 3,000 a day, and uploads them to the Web so the wearer can access them.

Oskar Kalmaru,
a co-founder of Memoto, said the company stresses to its customers "how it's actually a pretty crappy spycam: no remote control, no streaming, very visible and so on."

There is almost nothing individuals can do to prevent their activities from being recorded or tracked while in public, legal experts say.
Chris Conley,
a technology policy attorney at the American Civil Liberties Union of Northern California, says that while Google Glass is currently a primitive device, "it's something you could see evolving into a state of constant awareness of the environment, making it difficult for third parties to understand whether they're being analyzed or recorded."

But he added that he "can't think of anything that Google Glass could conceivably do that is actually going to run into legal concerns," unless perhaps someone creates an application that invades people's privacy by "seeing" underneath their clothes, similar to the passenger scans at U.S. airports.

Consumers and governments world-wide have grappled with some of these questions before with the discreet cameras on cellphones. When they first emerged in the early 2000s, some worried about their potential use for espionage and voyeurism. Businesses such as gyms banned their use.

And in 2004, Congress passed the Video Voyeurism Prevention Act without much opposition, which prohibits photographing a naked person without his or her explicit permission in a gym, dressing room, or other places that one expects "a reasonable expectation of privacy." (Violators face fines of up to $100,000 and up to a year in prison.)

Yet a decade later, camera-phones have become an accepted and relatively uncontroversial part of modern culture.

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